The invention relates to a valve which is open when unenergized and controllable by analog means, and is referred to hereinafter as a pressure regulating valve, in particular for pressure control in motor vehicle brake systems.
Already known from DE 101 54 257 A1, which is incorporated by reference, is a pressure regulating valve of the type indicated which is used as a wheel inlet valve or block valve, activatable by analog means, in motor vehicle brake systems, for which purpose:                a) the pressure regulating valve must be designed for the greatest possible precision using precise constructional elements, in particular a narrowly specified compression spring, or        b) the pressure regulating valve must be adjusted during production to defined function values, an increase or decrease of the working air gap in the electromagnet being used as a manipulated variable.        
In both cases the accuracy of the attainable specification is limited, since in case a) the production of more accurate components is not economically possible, while in case b), through the variation of the air gap, the position and tolerance of the opening-current characteristic curve can be configured optimally for only one pressure, the set pressure, while relatively large deviations occur for pressures remote from the set point, depending on the magnitude of the errors to be compensated.